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Analog Devices Inc. LTC1147LCS8-3.3#TRPBF
- Part No.:
- LTC1147LCS8-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147LCS8-3.3#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,735
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Product details
Overview
LTC1147LCS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, constant off-time current-mode step-down switching regulator controller driving an external P-channel MOSFET. It delivers a fixed 3.3V output with ±3% regulation over 5mA–2A load, supports 3.5V–14V input, achieves >95% efficiency at full load, and features Burst Mode™ operation for 160µA light-load quiescent current. It is used in battery-powered portable instruments and GPS systems requiring compact, low-noise DC/DC conversion.
For engineers reviewing the LTC1147LCS8-3.3#TRPBF datasheet, LTC1147LCS8-3.3#TRPBF pinout, LTC1147LCS8-3.3#TRPBF application, or LTC1147LCS8-3.3#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed 8-pin SOIC package mapping, real-world load regulation data (±65mV), and two field-validated alternative controllers for 3.3V buck applications.
Technical Context
The LTC1147LCS8-3.3#TRPBF implements a constant off-time current-mode architecture with internal 1.25V reference and programmable current-sense threshold (125–185mV). Its CT pin controls switching frequency via external capacitor, while ITH adjusts current comparator threshold to track load transients.
Burst Mode™ operation activates below ~15mV/RSENSE load current, reducing IQ to 160µA and enabling micropower shutdown (IQ < 20µA) via SHDN pin. The device maintains 100% duty cycle low-dropout regulation limited only by external MOSFET RDS(ON) and sense resistor resistance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (3.23–3.43V at 700mA), enabling direct replacement of 3.3V LDOs without feedback divider. |
| Input Voltage Range | 3.5V to 14V (16V absolute max), supporting single-cell Li-ion (4.2V) up to automotive 12V rail with margin. |
| Load Regulation | ±65mV (5mA–2A), ensuring stable 3.3V supply across wide dynamic loads in portable instrumentation. |
| Quiescent Current | 160µA in Burst Mode, delivering 2mW standby power at VIN=10V - critical for battery runtime extension. |
| Shutdown Current | <20µA when SHDN ≥ 0.8V, enabling deep sleep in GPS receivers and handheld medical devices. |
| Current Sense Threshold | 125–185mV (typ. 150mV), setting peak inductor current and defining maximum output capability with RSENSE. |
| Off-Time | 3.8–6.5µs (CT=390pF, ILOAD=700mA), determining minimum on-time and dropout behavior near VIN≈VOUT. |
Pinout & Package
Package: 8-lead plastic SOIC (S8), 150°C/W junction-to-ambient thermal resistance, RoHS-compliant and lead-free (TRPBF suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power input | Accepts 3.5–14V; requires local 100µF + 1µF ceramic decoupling to minimize switching noise injection. |
| CT (Pin 2) | Timing capacitor connection | Sets operating frequency; discharge current scales with VOUT to stabilize fSW vs. input voltage. |
| ITH (Pin 3) | Current comparator threshold control | Voltage applied here raises current trip point - used for adaptive current limiting or soft-start. |
| SENSE– (Pin 4) | Inverting current sense input | Connects to internal resistive divider; forms differential pair with SENSE+ to detect RSENSE voltage drop. |
| SENSE+ (Pin 5) | Non-inverting current sense input | Paired with SENSE–; built-in 25–150mV offset defines current trip threshold with external shunt. |
| SHDN/VFB (Pin 6) | Shutdown control / feedback reference | Grounded for normal operation; pulled high (>0.8V) for micropower shutdown; not used as VFB in fixed-3.3V version. |
| GND (Pin 7) | Analog and power ground | Must be split: one path to COUT (–) and Schottky cathode, second to CIN (–) - prevents ground bounce. |
| PDRIVE (Pin 8) | P-channel MOSFET gate driver | High-current push-pull output swinging from VIN to GND; drives Si4431DY-level gate charge (29–50nC). |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Reduces IQ to 160µA below ~300mA load, extending battery life in GPS trackers without sacrificing transient response. |
| Constant off-time architecture | Enables 100% duty cycle low-dropout regulation - VOUT tracks VIN down to VOUT ≈ VIN – ILOAD×RDS(ON) – ILOAD×RSENSE. |
| Logic-controlled shutdown | SHDN pin draws <5µA and accepts CMOS logic; enables system-level power sequencing in portable computers. |
| Internal 1.25V reference | Stable bandgap reference with 0.2–1µA feedback current - eliminates external reference IC in space-constrained designs. |
| Short-circuit protection | Automatically extends tOFF during overload, limiting average short-circuit current to IMAX = 150mV/RSENSE. |
Applications
| Portable Instrumentation | GPS Navigation Systems |
|---|---|
Use Scenario: Handheld multimeter with LCD backlight and microcontroller running on single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Step-down controller regulating 3.3V for MCU, ADC, and display driver from varying battery voltage. Use Value: Burst Mode™ maintains >90% efficiency at µA-level sleep currents while delivering 2A peaks for backlight strobes. |
Use Scenario: Automotive GPS receiver requiring clean 3.3V supply across cold-crank (6V) to alternator (14V) conditions. IC Role / Device Role / Timing Role: Primary DC/DC controller managing power delivery to RF front-end, baseband processor, and memory. Use Value: Wide 3.5–14V input range and 100% duty cycle operation ensure uninterrupted 3.3V output during engine start. |
| Notebook Subsystem Power | Cellular Baseband Modules |
Use Scenario: Secondary power rail for USB-C PD controller and sensor hub in ultrabook design. IC Role / Device Role / Timing Role: Efficient 3.3V generation from main 5V or 12V bus, co-located with high-speed digital circuitry. Use Value: Low 65mV load regulation and split-ground layout minimize noise coupling into sensitive analog sensors. |
Use Scenario: Power management for LTE modem baseband IC in smartphone, powered from shared PMIC rail. IC Role / Device Role / Timing Role: Dedicated 3.3V buck controller providing isolated, low-noise supply for RF calibration circuits. Use Value: 160µA Burst Mode IQ reduces idle power draw, directly improving talk-time and standby duration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1148CS8-3.3#TRPBF | Higher 500kHz typical switching frequency; lower 120µA Burst Mode IQ; same pinout and 3.3V fixed output. | Better suited for compact layouts requiring smaller L/C values; optimized for higher-frequency, lower-ripple designs. | Select when board area is constrained and EMI filtering must target >400kHz harmonics. |
| TPS54202DRCT | Integrated 28V 2A N-channel MOSFET; 4.5–28V input; adjustable output; no Burst Mode - uses D-CAP2 control. | Eliminates external FET and gate driver but lacks micropower shutdown; requires external feedback resistors. | Choose for simplified BOM and higher input voltage tolerance, accepting trade-off in light-load efficiency. |
Compared with LTC1147LCS8-3.3#TRPBF, LTC1148CS8-3.3#TRPBF offers superior light-load efficiency in identical footprint, while TPS54202DRCT trades external component count for reduced control flexibility and higher IQ at no load.
Availability
LTC1147LCS8-3.3#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, GPS navigation systems, and notebook subsystem power requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production lots.
Supply support for LTC1147LCS8-3.3#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains its legacy precision analog and power management portfolio with full datasheet, simulation model, and application note support.
The LTC1147 series was designed specifically for high-efficiency, low-quiescent-current step-down control in battery-powered portable electronics - emphasizing Burst Mode™ operation, wide input range, and minimal external component count.
FAQ
What is the minimum input voltage required for LTC1147LCS8-3.3#TRPBF to regulate 3.3V?
The LTC1147LCS8-3.3#TRPBF supports a minimum input voltage of 3.5V, as specified for the LTC1147L series. Below this, regulation cannot be guaranteed due to internal reference and comparator headroom limitations. At VIN = 3.5V, the device operates in 100% duty cycle mode, delivering VOUT ≈ VIN – ILOAD×(RDS(ON) + RSENSE), making external MOSFET RDS(ON) and sense resistor selection critical for maintaining 3.3V under load.
Does LTC1147LCS8-3.3#TRPBF require an external feedback resistor network?
No, the LTC1147LCS8-3.3#TRPBF is the fixed-output variant and does not require external feedback resistors. Its 3.3V regulation is achieved via internal resistive divider connected to SENSE– (Pin 4); Pin 6 (SHDN/VFB) serves only as shutdown control and is not used for voltage setting. This simplifies layout and eliminates resistor tolerance errors affecting output accuracy.
How does Burst Mode™ operation affect output voltage ripple in LTC1147LCS8-3.3#TRPBF?
In Burst Mode™, LTC1147LCS8-3.3#TRPBF produces 50mVP-P output ripple at zero load, as measured under specified test conditions. This low-frequency ripple results from periodic energy bursts into COUT rather than continuous switching. The ripple amplitude remains bounded and does not compromise regulation - it is a deliberate trade-off to achieve 160µA quiescent current while maintaining fast wake-up response to load steps.
Can LTC1147LCS8-3.3#TRPBF drive a logic-level P-channel MOSFET?
Yes, LTC1147LCS8-3.3#TRPBF can drive logic-level P-channel MOSFETs, but VIN must remain below the MOSFET's absolute maximum VGS rating. For example, with a –12V VGS(max) MOSFET, VIN must stay ≤ 12V. The PDRIVE (Pin 8) swings from VIN to GND, so exceeding VGS(abs max) risks gate oxide damage. Standard-threshold MOSFETs (VGS(TH) < –4V) are preferred for VIN > 8V applications.
What is the purpose of the ITH pin on LTC1147LCS8-3.3#TRPBF?
The ITH (Pin 3) on LTC1147LCS8-3.3#TRPBF sets the current comparator threshold voltage - raising ITH increases the current trip point, allowing dynamic adjustment of peak inductor current. It is commonly used for soft-start (ramping ITH from GND) or adaptive current limiting during inrush or fault conditions, without modifying RSENSE or altering the fixed 3.3V output regulation.
LTC1147LCS8-3.3#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 14V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1147LCS8-3.3#TRPBF FAQ
1.How can I place an order for LTC1147LCS8-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147LCS8-3.3#TRPBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC1147LCS8-3.3#TRPBF reliable?
The price and inventory of LTC1147LCS8-3.3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147LCS8-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1147LCS8-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147LCS8-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147LCS8-3.3#TRPBF?
LTC1147LCS8-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147LCS8-3.3#TRPBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC1147LCS8-3.3#TRPBF?
For technical support, including LTC1147LCS8-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147LCS8-3.3#TRPBF requirements.
6.How does Aetrix verify that LTC1147LCS8-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1147LCS8-3.3#TRPBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC1147LCS8-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1147LCS8-3.3#TRPBF?
All LTC1147LCS8-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147LCS8-3.3#TRPBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC1147LCS8-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LTC1147LCS8-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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